irq: refactor and clean up the free_irq() code flow

[cascardo/linux.git] / kernel / irq / manage.c

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index cd0cd8d..7a954b8 100644 (file)
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -397,7 +397,7 @@ int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
  * allocate special interrupts that are part of the architecture.
  */
 static int
-__setup_irq(unsigned int irq, struct irq_desc * desc, struct irqaction *new)
+__setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 {
        struct irqaction *old, **p;
        const char *old_name = NULL;
@@ -575,72 +575,79 @@ int setup_irq(unsigned int irq, struct irqaction *act)
 void free_irq(unsigned int irq, void *dev_id)
 {
        struct irq_desc *desc = irq_to_desc(irq);
-       struct irqaction **p;
+       struct irqaction *action, **p, **pp;
        unsigned long flags;
 
-       WARN_ON(in_interrupt());
+       WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
 
        if (!desc)
                return;
 
        spin_lock_irqsave(&desc->lock, flags);
+
+       /*
+        * There can be multiple actions per IRQ descriptor, find the right
+        * one based on the dev_id:
+        */
        p = &desc->action;
        for (;;) {
-               struct irqaction *action = *p;
+               action = *p;
+               pp = p;
 
-               if (action) {
-                       struct irqaction **pp = p;
+               if (!action) {
+                       WARN(1, "Trying to free already-free IRQ %d\n", irq);
+                       spin_unlock_irqrestore(&desc->lock, flags);
 
-                       p = &action->next;
-                       if (action->dev_id != dev_id)
-                               continue;
+                       return;
+               }
+
+               p = &action->next;
+               if (action->dev_id != dev_id)
+                       continue;
 
-                       /* Found it - now remove it from the list of entries */
-                       *pp = action->next;
+               break;
+       }
 
-                       /* Currently used only by UML, might disappear one day.*/
+       /* Found it - now remove it from the list of entries: */
+       *pp = action->next;
+
+       /* Currently used only by UML, might disappear one day: */
 #ifdef CONFIG_IRQ_RELEASE_METHOD
-                       if (desc->chip->release)
-                               desc->chip->release(irq, dev_id);
+       if (desc->chip->release)
+               desc->chip->release(irq, dev_id);
 #endif
 
-                       if (!desc->action) {
-                               desc->status |= IRQ_DISABLED;
-                               if (desc->chip->shutdown)
-                                       desc->chip->shutdown(irq);
-                               else
-                                       desc->chip->disable(irq);
-                       }
-                       spin_unlock_irqrestore(&desc->lock, flags);
-                       unregister_handler_proc(irq, action);
+       /* If this was the last handler, shut down the IRQ line: */
+       if (!desc->action) {
+               desc->status |= IRQ_DISABLED;
+               if (desc->chip->shutdown)
+                       desc->chip->shutdown(irq);
+               else
+                       desc->chip->disable(irq);
+       }
+       spin_unlock_irqrestore(&desc->lock, flags);
+
+       unregister_handler_proc(irq, action);
+
+       /* Make sure it's not being used on another CPU: */
+       synchronize_irq(irq);
 
-                       /* Make sure it's not being used on another CPU */
-                       synchronize_irq(irq);
-#ifdef CONFIG_DEBUG_SHIRQ
-                       /*
-                        * It's a shared IRQ -- the driver ought to be
-                        * prepared for it to happen even now it's
-                        * being freed, so let's make sure....  We do
-                        * this after actually deregistering it, to
-                        * make sure that a 'real' IRQ doesn't run in
-                        * parallel with our fake
-                        */
-                       if (action->flags & IRQF_SHARED) {
-                               local_irq_save(flags);
-                               action->handler(irq, dev_id);
-                               local_irq_restore(flags);
-                       }
-#endif
-                       kfree(action);
-                       return;
-               }
-               printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);
 #ifdef CONFIG_DEBUG_SHIRQ
-               dump_stack();
-#endif
-               spin_unlock_irqrestore(&desc->lock, flags);
-               return;
+       /*
+        * It's a shared IRQ -- the driver ought to be prepared for an IRQ
+        * event to happen even now it's being freed, so let's make sure that
+        * is so by doing an extra call to the handler ....
+        *
+        * ( We do this after actually deregistering it, to make sure that a
+        *   'real' IRQ doesn't run in * parallel with our fake. )
+        */
+       if (action->flags & IRQF_SHARED) {
+               local_irq_save(flags);
+               action->handler(irq, dev_id);
+               local_irq_restore(flags);
        }
+#endif
+       kfree(action);
 }
 EXPORT_SYMBOL(free_irq);
 
@@ -687,11 +694,12 @@ int request_irq(unsigned int irq, irq_handler_t handler,
         * the behavior is classified as "will not fix" so we need to
         * start nudging drivers away from using that idiom.
         */
-       if ((irqflags & (IRQF_SHARED|IRQF_DISABLED))
-                       == (IRQF_SHARED|IRQF_DISABLED))
-               pr_warning("IRQ %d/%s: IRQF_DISABLED is not "
-                               "guaranteed on shared IRQs\n",
-                               irq, devname);
+       if ((irqflags & (IRQF_SHARED|IRQF_DISABLED)) ==
+                                       (IRQF_SHARED|IRQF_DISABLED)) {
+               pr_warning(
+                 "IRQ %d/%s: IRQF_DISABLED is not guaranteed on shared IRQs\n",
+                       irq, devname);
+       }
 
 #ifdef CONFIG_LOCKDEP
        /*
@@ -717,7 +725,7 @@ int request_irq(unsigned int irq, irq_handler_t handler,
        if (!handler)
                return -EINVAL;
 
-       action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
+       action = kmalloc(sizeof(struct irqaction), GFP_KERNEL);
        if (!action)
                return -ENOMEM;